Take a look at this link dojo tester. Select the Tree or Rootless Tree in the accordian control on the left-hand side. This shows that multiple levels are possible in a navigation tree using dojo. I am hoping that this and some other dojo features are more fully implemented in mendix version 3 when it is released.
Also take a look at these enhanced data grids. Vertical and horizontal scrollbars in datagrids, a better way of selecting multiple rows (shift-click, control click or swipe), nested sorting, re-ordering columns etc. ... let's hope...